Icebreaker



July 24, 1962 w s ETAL 3,045,628

ICEBREAKER Filed 90). d212, 1958 HEINRICH M55 JOHN/l1 5mm; OTTO G n ATTORNEY nit-ed rates It has been proposed to break ice by means of a ship undergoing periodical pitching motions when in use. These pitching motions are on its natural frequency, or, at least, not far from it. I have improved this operation by bringing the ships periodical pitching motions to that frequency, which is fixed by the stillness of the ice to be broken. Those installations to produce periodic pitching motions are adjusted for this frequency. For both types the. form and mass of the ship will affect that frequency which is to be adjusted.

The present invention is concerned with a further improvement in this field and principally differs from the above mentioned embodiments because the form and mass of the entire ship are not essential for the frequency to be chosen. The invention is particularly concerned with means to solve problems which have arisen from practical experience in particularly thick ice. Valuations of the thickness of ice require considerations concerning the ships dimensions; e.g. tor a ship of 300 t. (metric tons), an ice-sheet of 1 m. and more will be called thick in the sense of this application.

A ship of these dimensions, depending only on the thrust of its own propeller, will not be able to move ahead continuously in thick ice. It will rather shove up on the ice and, according to the intensity of the propeller thrust, it will come to a halt more or less aloft on the ice. In such a case, the bow of the ship will be almost rigidly connected to the ice. This fact is utilized by the invention. In this case the application of the means of the previously-proposed arrangements would not yield a suflicient solution, because the ice is too thick, and such prior means are not sufficient to break the ice.

According to the invention the installations to produce ice-breaking forces are concentrated in that area where they can immediately act on the ice, i.e. in or at the bow of the ship.

The direction of these forces is vertical, i.e. at right angle to the ice-sheet and the forces are produced, for example, by known contrarotating unbalanced masses, which are adjusted in phase in such a manner, so that they compensate each other in the horizontal direction, but are additive in the vertical direction. The vertical direction is the most eflicient arrangement, as it can break ice with the least energy.

In the accompanying drawing,

FIG. 1 is a side elevational view, partly in section, of a first embodiment of the invention;

FIG. 2 is a plan view of the construction of FIG. 1;

FIG. 3 is a side elevational view of another embodiment; and

FIG. 4 is a similar view of a further embodiment.

A device to create vertical pitching forces in the bow of a ship is shown, for example, in FIG. 1. The unbalanced weights a and b-both of the same sizecontrarotate around the axis 0, which is firmly attached to the ship, as is shown by the arrows. The unbalanced weights contrarotate with the same angular velocity in such manner that they will meet above and below on the line d-d. Thus, the horizontally directed centrifugal forces of the unbalance weights a and b, working on the force-body via axis c, are compensated. The vertically directed centrifugal forces are additive however. The moving forces of these two unbalanced weights can be achieved in any appropriate way by well-known means. FIG. 2, e.g., shows a drive in horizontal plan. On the axis 0, which is firmly connected to the ship, there are rotatably mounted two circular disks 1 of the same size, being the supporting structure for the unbalanced weights a and [2. Both disks are driven in opposite directions, but at the same angular velocity by a belt drive In and an electric motor n. The necessary precision of synchronism of both unbalanced weights can be achieved electricaly by suitable control of both motors. Instead of the belt drive, however, toothed gearing or chain gearing may be employed. Synchronisrn of both disks 1 is then achieved mechanically.

Without considerably altering the character of this invention, the installation will operate with the unbalanced weights a and h each rotating in the opposite direction. Moreover, there would not be a substantial loss of pitching force, if the centers of gravity of the unbalanced weights a and b did not pass each other on line d-d, but on a line, which is inclined a bit forward or backward.

In practice, that part of the ship which does not lie on the ice, does not support the breaking eflect. The character of the invention would not be changed, if that part of the ship, which does not lie on the ice, were arranged as far away from the bow of the ship and from the unbalance mechanism, as possible, so as to vibrate separately. As a result there will be no disturbance by vibration in the aft and middle part of the ship.

This may be achieved, for instance, by cutting the bow p of the ship containing the pitching mechanism from the rest of the ship as shown in FIG. 3; both parts of the ship have to be closed by watertight bulkheads e, and are connected to each other by straps f, pivoted on a horizontal axis. In this embodiment an elastic suspension g between the two straps at the after part of the ship makes the pitching motion, caused by the pitching mechanism in the bow of the ship, to pass not directly but to be tempered as far as possible.

The unbalance device does not have to be installed directly in the bow of the ship. It may be connected to the bow in any convenient way. Such an embodiment is shown in FIG. 4 wherein the unbalance device has been installed in a floating body s and is connected to the bow of the icebreaker by arms h. The arms h are firmly fixed to the floating body and they are formed in such a way that the ship shoves the floating body be tween these arms. These arms may be coupled to the bow of the ship on the axis i, as shown. The arms can rest on the elastic suspension, which is fixed to the ship.

In the embodiment according to FIG. 4, the weight of the ship takes part in the breaking effect of the floating body and its pitching device by means of the arms h and the elastic suspension k. Without altering the character of the invention, the floating body and its pitching device may be formed sufficiently large to break the ice by its own displacement. [In such a case, the connection to the ship may be eflected in another convenient manner.

The installation of the unbalance or pitching device in a separate floating body may be advantageous. The pitching floating body can be formed in a manner particularly suitable for breaking. It can have a breadth that permits ships of greater dimensions to follow. On the other hand, a plurality of floating bodies can be employed side by side, if desired.

The floating body with the unbalance or pitching device may be mounted on the ship during ice-breaking service only, and dismantled during the rest of the time.

What we claim is:

1. An ice breaker having means for inducing periodic pitching movements, said means comprising a plurality of unbalanced masses mounted for rotation in a vertical plane about a common axis disposed at right angles to the vertical longitudinal plane of the ice breaker, said means being associated with the bow of the ice breaker, and said means for inducing periodic pitching movements being effective to produce an ice-breaking force which is large relative to the weight of the ship with which it is associated and being effective in a ship of 300 metric tons to break ice of a thickness of 1 meter and upwards.

2. An ice breaker having means for inducing periodic pitching movements, said means comprising a plurality of unbalanced masses mounted for rotation in a vertical plane about a common axis disposed at right angles to the vertical longitudinal plane of the ice breaker, said masses being mounted for rotation in opposite directions at the same angular velocity and being relatively related to meet on the vertical line passing through said axis when said masses are at the top and at the bottom of their paths of rotation, whereby the forces induced by the rotation of said masses compensate each other in the horizontal direction and are additive in the ventical direction, said means being associated with the bow of the ice breaker, and said means for inducing periodic pitching movements being efiective to produce an ice-breaking force which is large relative to the weight of the ship with which it is associated and being eflective in a ship of 300 metric tons to break ice of a thickness of 1 meter and upwards.

3. An ice breaker having means for inducing periodic pitching movements, said means comprising unbalanced masses mounted for rotation about an axis disposed at right angles to the vertical longitudinal plane of the ice breaker, said means being mounted upon a floating body disposed forwardly of the ice breaker and said floating body being elastically connected to the ice breaker.

References Cited in the file of this patent UNITED STATES PATENTS 614,142 Steiner Nov. 15, 1898 1,071,735 Haagenson Sept. 2, 1913 1,571,264 Gretsch Feb. 2, 1926 1,675,560 Jubien July 3, 1928 1,809,288 Sample June 9, 1931 20 2,715,380 Archer Aug. 16, 1955 FOREIGN PATENTS 26,098 Great Britain Nov. 9, 1910 

